iphone - 使用 UIImage imageWithData:NSData dataWithContentsOfFile 时不显示图像

Question

下面的代码没有显示从网上下载并写入我的应用程序文档目录的图像。我检查了iphone的模拟器文件目录里面，下载的文件是存在的。但图像不显示。

尝试使用 添加资源图像UIImage *imgBack = [UIImage imageNamed:@"btn-back.png"];时，uiimageview 显示 image.bu 从在线下载并存储在应用程序目录中的图像不显示图像。

请告诉我，谢谢

NSString *workSpacePath=[[self applicationDocumentsDirectory] stringByAppendingPathComponent:theFileName];
NSLog(@"%@ workSpacePath ",workSpacePath);
if ( workSpacePath ){

        //--------------
       UIImage *imgBack = [UIImage imageNamed:@"btn-back.png"];
       imageView1 = [[[UIImageView alloc] initWithFrame:CGRectMake(0,0,20,20)] autorelease];
       [imageView1 setBackgroundColor:[UIColor grayColor]];

       imageView1.image = [UIImage imageWithData:[NSData dataWithContentsOfFile:workSpacePath]];
       [cell addSubview:imageView1];
}

Answer 1

而不是首先将文件转换为NSData，您可以使用

[UIImage imageWithContentsOfFile:filePath]

直接加载一个image给定的路径。

Answer 2

试试这个，这对我来说非常有用：

 - (void)viewDidLoad
{
     [super viewDidLoad];

     NSURL *url1 = [NSURL URLWithString:@"http://mobiledevelopertips.com/images/logo-iphone-dev-tips.png"];
    UIImage *image = [UIImage imageWithData: [NSData dataWithContentsOfURL:url1]];

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,     NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *savedImagePath = [documentsDirectory stringByAppendingPathComponent:@"savedImage.png"];

    NSData *imageData = UIImagePNGRepresentation(image);
    [imageData writeToFile:savedImagePath atomically:NO]; 

    NSArray *paths1 = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory1 = [paths1 objectAtIndex:0];
    NSString *workSpacePath = [documentsDirectory1 stringByAppendingPathComponent:@"savedImage.png"]; 
    NSLog(@"%@ workSpacePath ",workSpacePath);

if ( workSpacePath )
     {
        imageView1 = [[UIImageView alloc] initWithFrame:CGRectMake(20,20,20,20)];
        [imageView1 setBackgroundColor:[UIColor grayColor]];

        imageView1.image = [UIImage imageWithData:[NSData dataWithContentsOfFile:workSpacePath]];
        [self.view addSubview:imageView1];

    }
}